The Arrondissement of Ath (; ) is one of the seven administrative arrondissements in the Walloon province of Hainaut, Belgium. It is not a judicial arrondissement. Two of its municipalities, Brugelette and Chièvres, are part of the Judicial Arrondissement of Mons, while the others are part of the Judicial Arrondissement of Tournai.
The Administrative Arrondissement of Ath consists of the following municipalities:
The three municipalities of the Arrondissement of Soignies (Enghien, Lessines and Silly) are integrated into the Arrondissement of Ath on January 1, 2019.